Chloride is a type of electrolyte. It works with other electrolytes such as potassium, sodium, and carbon dioxide (CO2) to help keep the proper balance of body fluids and maintain the body's acid-base balance.

This article discusses the laboratory test to measures the amount of chloride in the fluid portion (serum) of the blood.

See also:

• Chloride in diet
• Chloride test - urine
• Sweat chloride test
• Urine electrolytes test

Your doctor may order this test if you have signs of a disturbance in your body's fluid level or acid-base balance.

This test is usually ordered along with other blood tests such as a metabolic panel (CHEM-7 or CHEM-20).

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Your doctor may tell you to temporarily stop taking certain drugs that can affect test results.

Drugs that may increase serum chloride measurements include:

• Acetazolamide
• Ammonium chloride
• Androgens
• Cortisone
• Estrogen
• Guanethidine
• Methyldopa
• Non-steroidal anti-inflammatory drugs (NSAIDs)

Drugs that may lower serum chloride measurements include:

• Aldosterone
• Bicarbonates
• Certain diuretics
• Triamterene

Never stop taking medication without first talking to your doctor.